This story appears on the Mar. 26, 2012 cover of Forbes as 'American Booty'.

Sara Blakely stands topless at a conference room table. It’s Monday morning at the Spanx headquarters in Atlanta, and the founder of the hosiery company has been in a product development meeting for all of five minutes before walking out abruptly. She returns a minute later in nothing but a lacy taupe bra with black pants and beige wedges and adjusts herself in a full-length mirror, worrying aloud about the metal clasps on this early prototype. Will they create lumps under her clothes? Her CEO, Laurie Ann Goldman — petite and glamorous in a leopard print shift dress — tugs on Blakely’s straps.

The conference room looks like a boudoir designed by Willy Wonka: a jar of gum balls here, a loud houndstooth print there. Blakely hardly blinks in the presence of five colleagues and me as she removes the bra and tries on a second prototype. She’s been getting half-naked in public for the last decade, controlling every detail of the new category in women’s retail—shapewear—that she created from a one-product wonder sold out of her apartment.

Today Spanx is to slimming undergarments what
Kleenex is to tissues: a brand that stands for the category. It nets an estimated 20% on revenue just south of $250 million. In recent months four Wall Street investment banks separately valued Spanx at an average $1 billion, a sum Forbes corroborated with the help of industry analysts. Blakely owns 100% of the private company, has zero debt, has never taken outside investment and hasn’t spent a nickel on advertising. At 41 she’s the youngest woman to join this year’s World’s Billionaires list without help from a husband or an inheritance. She is part of a tiny, elite club of American women worth ten figures on their own, including Oprah Winfrey and Meg Whitman.

Lots of women, from Betty Grable to Kim Kardashian, have put their butts on the line to plump their profiles and profits. Far fewer have had to overcome three phobias—fear of heights, fear of flying and stage fright—to master the art of selling. Blakely is on the road “always,” she says. She feels dizzy in tall buildings (it doesn’t help to have a Manhattan condo on the 37th floor) and often cries in midair. She’s unwilling to board a plane without her iPod, so she can play the same Mark Knopfler song, “What It Is,” at every takeoff. “I have sweaty palms, panic attacks, my heart’s racing,” says Blakely, whose Floridian roots you occasionally hear in her “Ah” for “I.” She once had to muster the courage to hawk her wares 6 to 12 times a month on home shopping channel QVC; now that Spanx is so well-known, it’s maybe once a month but for hours at a time. Blakely had early practice wrestling with anxiety when she occasionally did standup comedy. “Every time I went onstage I was so terrified I almost threw up,” she recalls. “I learned why they call it the greenroom.”

Spanx started as a one-woman show. In her first year Blakely shilled her new invention from a folding table in the foyer of Neiman Marcus, with a giant before-and-after photo of her derriere in cream slacks and bikini briefs underneath in one shot (an embarrassingly obvious Maginot Line) and $30 Spanx Power Panties (et voilà! no more line) in the other.

Over the last couple of years Spanx has depended less on Blakely’s face—and other body parts—to shift its shapers and stay ahead of a handful of copycats. The company is now run by a team of 125, only 16 of them men. It sells 200 products in 11,500 department stores, boutiques and online shops in 40 countries. Distributors worldwide clamor to get on the stockist list. “With international, we’re just warming up,” says Goldman.